Empirical model of annual nitrous oxide emissions from open-lot beef cattle feedyard pens (Version 2)

Authors: Parker, David; CASEY, KENNETH - Texas A&M Agrilife; CORTUS, ERIN - University Of Minnesota; Min, Byeng Ryel; Waldrip, Heidi; Woodbury, Bryan; Spiehs, Mindy

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 4/29/2019
Publication Date: 7/9/2019
Citation: Parker, D.B., Casey, K.D., Cortus, E.L., Min, B., Waldrip, H., Woodbury, B.L., Spiehs, M.J. 2019. Empirical model of annual nitrous oxide emissions from open-lot beef cattle feedyard pens (Version 2). In: Proceedings of the 2019 ASABE Annual International Meeting, July 5-7, 2019, Boston, Massachusetts. Paper No. 1900299. p. 1-18.

Interpretive Summary: Nitrous oxide is a greenhouse gas that has been linked to climate change. High concentrations of nitrogen and carbon make livestock manure at beef feedyards a source of nitrous oxide emissions. Scientists from USDA-ARS (Bushland, Texas), University of Minnesota (St. Paul, Minnesota), and Texas A and M AgriLife Research (Amarillo, Texas) developed a computer model to help predict and study nitrous oxide emissions from feedyard pen surfaces. Using 23 years of weather data from 1996 to 2018, they showed that emissions during the three warmest months of June, July, and August accounted for more than half of annual emissions. Compared to removing manure from pens once per year, removing manure 2, 3, or 4 times per year reduced annual N2O emissions by 39.8, 56.1, or 62.8 percent, respectively. The most effective time for manure removal was in May and June.

Technical Abstract: Nitrous oxide (N2O) is a greenhouse gas with a higher global warming potential than carbon dioxide. About 12 million beef cattle are raised annually in the semiarid Southern High Plains on open-lot, earthen-surfaced pens. Feces and urine are deposited directly on the pen surface and contribute to N2O emissions. The objectives of this research were to: 1) develop a model for estimating annual N2O emissions from open-lot beef cattle feedyard pens in the Southern High Plains, and 2) assess various manure removal strategies for reducing N2O emissions. Empirical regression equations derived from laboratory and field studies were used to predict N2O emissions based on daily precipitation and temperature. The model accounted for water added to the pen surface from urine and feces, and allowed for different times and frequencies for pen cleaning. Feedyard runoff and infiltration were estimated using daily weather data for the 23 year period from 1996 to 2018. Average annual precipitation was 367 mm per year, with range of 136 to 658 mm per year and daily maximum of 102 mm per day. Emissions of N2O were highest in the few days following precipitation events in the warm summer months. Timing of pen cleaning was important for one cleaning per year, where annual N2O emissions ranged from 0.196 kg N per animal per year for cleaning on 1 May to 0.533 kg N per animal per year for cleaning on 1 Oct. The optimum timing for two cleanings per year was 1 Jun and 1 Dec (0.118 kg N per animal per year). Timing had little effect on annual emissions for three or more cleanings. Cleaning pens 3, 4, 6, or 12 times per year resulted in annual N2O emissions of 0.086, 0.073, 0.063, or 0.057 kg N per animal per year. Emissions from urine and feces deposition accounted for 29.0 and 7.1 percent of overall emissions, respectively. As compared to one pen cleaning per year on 1 May, cleaning pens 2, 3, 4, 6, or 12 times per year reduced annual N2O emissions by 39.8, 56.1, 62.8, 67.9, or 70.9 percent, respectively.